The present invention relates to the field of communications, and, more particularly, to phased array antenna systems and related methods.
Antenna systems are widely used in both ground based applications (e.g., cellular antennas) and airborne applications (e.g., airplane or satellite antennas). For example, so-called xe2x80x9csmartxe2x80x9d antenna systems, such as adaptive or phased array antenna systems, combine the outputs of multiple antenna elements with signal processing capabilities to transmit and/or receive communications signals (e.g., microwave signals, RF signals, etc.). As a result, such antenna systems can vary the transmission or reception pattern (i.e., xe2x80x9cbeam shapingxe2x80x9d or xe2x80x9cspoilingxe2x80x9d) or direction (i.e., xe2x80x9cbeam steeringxe2x80x9d) of the communications signals in response to the signal environment to improve performance characteristics.
A typical phased array antenna system may include, for example, a host processor for generating host commands and a central controller for processing the host commands and generating beam control commands (e.g., beam steering control commands and/or beam spoiling central commands) for the antenna elements based thereon. One or more element controllers may be used for controlling the antenna elements based upon the beam control commands. In larger phased array antenna systems, subarray controllers may also be connected between groups of element controllers and the central controller to aid in beam control command processing and signal distribution, for example.
One problem that may become particularly acute in large phased array antenna systems is that of efficiently distributing the beam control commands from the central controller to the subarray controllers. More particularly, a communications bus (e.g., a serial bus) is typically used to connect the central controller and subarray controllers. Yet, numerous beam control commands other than just beam steering/spoiling commands may also need to be sent via the communications bus, such as operating frequency commands, temperature compensation commands, and telemetry request commands, for example. Furthermore, telemetry data may also need to be collected from the various antenna elements and sent to the central controller via the communications bus.
Several prior art approaches exist for distributing host commands to phased array antenna elements. Perhaps the most straightforward approach is to have the central controller perform essentially all of the beam command processing and send respective beam control commands for each of the antenna elements. Yet, this approach is highly susceptible to the above noted bandwidth problems, especially when fast beamsteer or beam spoiling updates are required. To attempt to compensate for the bandwidth shortfall by using a faster communications bus could increase costs and also result in decreased reliability.
Yet another prior art approach is to use fairly sophisticated subarray processors and essentially pass the host commands along through the central controller to the subarray processors. While this may alleviate bandwidth problems somewhat, the subarray controllers required to implement this approach would need to be fairly complex to perform the requisite processing (e.g., trigonometric calculations) on the host commands. This may lead to increased power consumption and costs if many such subarray controllers are used.
One particularly advantageous prior art approach is disclosed in U.S. Pat. No. 5,990,830 to Vail et al. entitled xe2x80x9cSerial Pipelined Phased Weight Generator for Phased Array Antenna Having Subarray Controller Delay Equalization,xe2x80x9d which is assigned to the present assignee and hereby incorporated herein in its entirety by reference. A central controller receives digitally formatted antenna beam steering data, for example, from a host processor and executes the requisite trigonometric calculations to transform the beam steering data into phase gradient data. Subarray controllers convert the phase gradient data from the central controller into sets of phase control data each for controlling a respective phase shifter, for example. In turn, the phase shifters drive respective phased array antenna elements.
This approach represents a significant advancement in the art in that the central controller does not have to generate all of the respective phase control data sets, which would likely require a very fast (and potentially unreliable) communications bus. Yet, the subarray controllers do not have to perform the more complex trigonometric processing, and thus their complexity need not be as great as in the second prior art approach discussed above. Nonetheless, with an ever increasing number of antenna elements and beam control commands being implemented in phased array antenna systems, even greater bandwidth utilization efficiency may be desirable in many applications.
In view of the foregoing background, it is therefore an object of the present invention to provide a phased array antenna system with prioritized beam control command and data transfer and related methods.
This and other objects, features, and advantages in accordance with the present invention are provided by a phased array antenna system including a substrate and a plurality of phased array antenna elements carried thereby, and a plurality of subarray controllers for controlling respective groups of phased array antenna elements (or groups of individual element controllers). The phased array antenna system may further include a central controller for generating priority beam control commands and non-priority beam control commands for the subarray controllers, and a communications bus connecting the subarray controllers to the central controller.
Additionally, the central controller may send the priority beam control commands to the subarray controllers via the communications bus on a substantially real time basis with time gaps therebetween. The central controller may also send the non-priority beam control commands to the subarray controllers via the communications bus during the time gaps. As a result of this beam control command prioritization, a more efficient use of the communications bus is achieved with respect to prior art approaches.
More particularly, the central controller may include a priority first-in, first-out (FIFO) device for storing and outputting the priority beam control commands and a non-priority FIFO device for storing and outputting the non-priority beam control commands. The central controller may further include an arbiter for selectively connecting the outputs of the priority FIFO device and the non-priority FIFO device to the communications bus.
In addition, the subarray controllers may collect telemetry data for respective groups of phased array antenna elements and send the telemetry data to the central controller via the communications bus. The central controller may further include a telemetry FIFO device connected to the arbiter, and the arbiter may selectively connect the telemetry FIFO device to the communications bus during the time gaps for storing the telemetry data.
The priority beam control commands may include at least one of beam steering angles or phase gradient commands, beam spoiling commands, and operating frequency commands, and the non-priority beam control commands may include at least one of temperature compensation commands and telemetry request commands, for example. Additionally, the priority beam control commands may be the same for all of the subarray controllers, and the non-priority beam control commands may also be the same for all of the subarray controllers. Further, each subarray controller may convert the priority and non-priority beam control commands into commands for respective phased array antenna elements connected thereto.
The phased array antenna system may also include a host processor for generating host commands, and the central controller may generate the priority beam control commands based upon the host commands. The phased array antenna system may further include a respective element controller for controlling each of the phased array antenna elements.
A method aspect of the invention is for providing beam control commands to a plurality of subarray controllers in a phased array antenna system. The method may include generating priority beam control commands and non-priority beam control commands for the subarray controllers. Further, the method may also include sending the priority beam control commands to the subarray controllers on a higher time priority basis than the non-priority beam control commands.